1. Field
Embodiments relate to a pixel and an organic light emitting display using the same, and more particularly, to a pixel capable of displaying an image with uniform brightness and an organic light emitting display using the same.
2. Description of the Related Art
Recently, various flat panel displays (FPD) capable of reducing weight and volume that are disadvantages of cathode ray tubes (CRT) have been developed. The FPDs include liquid crystal displays (LCD), field emission displays (FED), plasma display panels (PDP), and organic light emitting displays.
Among the FPDs, the organic light emitting displays display images using organic light emitting diodes (OLED) that generate light by re-combination of electrons and holes. The organic light emitting display has high response speed and is driven with low power consumption.
The organic light emitting display includes a plurality of pixels arranged at intersections of a plurality of data lines, scan lines, and power supply lines in a matrix. Each of the pixels commonly includes an organic light emitting diode (OLED) and a driving transistor for controlling the amount of current that flows to the OLED. The pixels supply currents from the driving transistors to the OLEDs to correspond to data signals to generate light components with predetermined brightness components.
However, as illustrated in FIG. 1, when a white gray scale is displayed after realizing a black gray scale in a conventional pixel, light with lower brightness than desired brightness is generated in a period of about two frames. In this case, an image with desired brightness is not displayed by the pixels to correspond to the gray scales. Therefore, uniformity of brightness is deteriorated so that picture quality of a moving picture is deteriorated.
As a result of experiment, in the organic light emitting display, deterioration of a response characteristic is caused by the characteristic of the driving transistor included in the pixel. That is, the threshold voltage of the driving transistor is shifted to correspond to the voltage applied to the driving transistor in a previous frame period so that light with desired brightness is not generated in the current frame.
In addition, in the conventional organic light emitting display, the OLED is deteriorated to correspond to use time. When the OLED is deteriorated, due to a change in efficiency, an image with desired brightness is not displayed. With the lapse of time, the OLED is deteriorated so that light with low brightness is generated to correspond to the same data signal.